Paint removal system for artificial grass

ABSTRACT

A method and device are provided for removing painted field markings from a synthetic grass surface including at least a sheet backing and a plurality of synthetic grass fibers extending upward thereform. The method comprise the steps of applying a paint-dissolving solvent to a region of the synthetic grass surface having the painted field markings thereon, brushing the region using at least one rotating brush to abrade paint coated on the synthetic grass fibers, and spraying the region with pressurized water.

TECHNICAL FIELD

The present invention relates generally to a method and system forremoving painted lines and other markings from an artificial turfsurface.

BACKGROUND OF THE INVENTION

Traditionally, either permanent inlaid fibers of a contrasting colour orpermanent paint have been used to create field markings on artificialgrass surfaces. However, permanent inlaid fibers do not provide fieldflexibility, as conversion between marking arrangements of differentsports is generally not possible. This significantly reduces thepracticality of the artificial grass surface, as the field surfacecannot easily be used for alternate purposes which may require differentmarking schemes. While the inlaid fibers, or sections of turf havingmarkings defined therein, can be replaced to convert the artificialgrass surface from one use to another, this is impractical, expensiveand time consuming. As is painting over the inlaid fibers with a paintcolour, such as green, which matches the colour of the field.

Painted markings are therefore much more practical, however they must beable to be removed when required, such that the artificial grass surfacecan be converted from one intended use to another. However, completeremoval of the permanent paint applied to the fibers of the artificialgrass surface has previously been problematic, often leaving “ghost”markings in place where lines or symbols have been removed. Further, theharsh scrubbing which is often used, using a wire brush or high pressurespray for example, in order to remove painted markings from theartificial grass surface can be significantly damaging the syntheticgrass fibers. This causes premature wear of the field surface in theseregions. As lines or other markings are generally removed and repaintedconsistently in the same locations on the field surface, this wearcauses visual indications of the removed markings in addition to the“ghost” paint markings. Paints which are less permanent are accordinglyless difficult to remove, and therefore less wear is caused to thesynthetic fibers as a result of the regular removal of markings in thesame locations. However, while easier to remove, such more temporarypaints can also more easily become dulled or worn away by rainfall orregular field use, thereby necessitating unwanted repainting. Suchadditional painting can cause the paint to cake onto the artificialgrass surface, which can cause painted sections of the turf to becomeabrasive and slippery to players using the artificial grass surface.Additionally, the caked on paint can eventually cause permanent marks onthe synthetic grass fibers which cannot be removed.

It would therefore be desirable to be able to easily and completelyremove field markings, without causing undue wear to the syntheticfibers of the artificial grass, such that the playing surface can beefficiently modified as required to permit conversion between fields ofdifferent sporting activities without leaving residual paint from aprevious marking scheme. Accordingly, the artificial grass surface canprovide a multi-purpose athletic field which, at any one time,aesthetically appears to be dedicated to a single sport. By being ableto remove all traces of previously painted markings, the overallappearance of the synthetic grass turf facility is enhanced withoutdegrading the life of the synthetic fibers. The enhanced visualappearance is especially important for fields to be used duringtelevised events.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a system and processfor removing painted field markings from a synthetic grass surface.

It is another object of the present invention to remove painted fieldmarkings from a synthetic grass surface without causing undue wear tothe synthetic grass fibers.

It is another object of the present invention to remove painted fieldmarkings from a synthetic grass surface such that substantially littlevisible paint residue remains thereon.

Therefore, in accordance with the present invention, there is provided adevice for removing painted field markings from a synthetic grasssurface including at least a sheet backing and a plurality of syntheticgrass fibers extending upward therefrom, the device comprising: adisplaceable vehicle adapted to move over the synthetic grass surface;at least one rotating brush operatively connected to the vehicle, therotating brush being engageable with the synthetic grass surface suchthat bristles-thereof contact the synthetic grass fibers of thesynthetic grass surface; a solvent nozzle, disposed forward of therotating brush and aligned therewith, for spraying a paint-dissolvingsolvent onto the synthetic grass surface in front of the rotating brush;and at least one water nozzle disposed on the vehicle adjacent therotating brush for directing a pressurized water spray onto thesynthetic grass surface proximate to the bristles of the rotating brush.

There is also provided, in accordance with the present invention, amethod of removing painted field markings from a synthetic grass surfaceincluding at least a sheet backing and a plurality of synthetic grassfibers extending upward therefrom, the method comprising the steps of:i)applying a paint-dissolving solvent to a region of the synthetic grasssurface having the painted field markings thereon; ii)brushing theregion using at least one rotating brush to abrade paint coated on thesynthetic grass fibers; and iii)spraying the region with pressurizedwater.

Field markings on artificial infilled grass are accordingly easilyremovable by first dissolving the paint using an appropriate solvent,brushing the synthetic fibers using a rotating brush, and-usingpressurized water spray to flush the totally removed paint material fromthe synthetic fibers, down into and through the artificial grass infillpile and backing. This paint removal system substantially eliminatesghosting on the field surface after the line markings have been removedby minimizing any visible residual paint particles, such that whateverevent is played on the field, the markings are unique and notovershadowed by lines from a previous event or sports activity.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will becomeapparent from the following detailed description, taken in combinationwith the appended drawings, in which:

FIG. 1 is a side elevation sketch of a device for removing painted fieldmarkings from a synthetic grass surface in accordance with the presentinvention.

FIG. 2 is a side perspective view of the device of FIG. 1.

FIG. 3 is a perspective view of the device of FIG. 1.

FIG. 4 is a perspective view of a device for removing painted fieldmarkings from a synthetic grass surface in accordance with a secondembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The paint removal device of the present invention permits removal ofpaint from a synthetic grass surface 13 having a plurality of syntheticgrass fibers 15 extending upward from a sheet backing 17 and an infilllayer 19 of particulate material interstitially disposed between theupstanding synthetic grass fibers 15. The paint removal device 10 ispreferably used for removing painted field markings from a syntheticgrass surface 13 used as a athletic field, such as in a stadium or otherathletic facility. Field markings as defined herein is intended toinclude lines, logos, lettering and other painted markings applicable toa synthetic grass surface. The painted field marking removal device 10accordingly permits a green or other coloured athletic field comprisedof a synthetic grass surface 13 to be easily adapted for multiple uses.Using the paint removal device, all of the painted lines and-otherpainted field markings applied to the synthetic grass surface 13 can beremoved, such that substantially no visible remnants of the markings areleft behind on the field surface. The necessary lines and/or fieldmarkings for an alternate sport or use can be subsequently applied tothe synthetic grass surface 13. The paint removal device is accordinglycapable of removing more resistant paints which are designed to be longlasting and which are otherwise difficult to fully remove withoutcausing damage to the synthetic grass fibers 15.

Referring to FIGS. 1 to 3, the paint removal device 10, preferablyadapted for removal lines from an athletic field surface, comprisesgenerally a vehicle 12 having a forwardly extending cantilevered supportbeam 14 securely fixed thereto and projecting outward from one side ofthe vehicle 12. A brush engaging mechanism 16 is engaged with thesupport beam 14 and includes two pivoting links 18 pivotably connectedat opposed ends thereof to the support beam 14 and a lower link member20, such that a four bar mechanism is formed. Accordingly, the lowerlink member 20 can be raised or lowered relative to the synthetic grasssurface 13 by pivoting the links 18 with respect to the support beam 14,which is fixed relative to the vehicle 12. The lower link member 20thereby remains substantially parallel to the support beam 14 throughoutthe vertical movement thereof. An actuator 21 is provided to pivot thelinks 18 thereby raising and lowering the lower link member 20.

Three rotating brushes 24 are operatively connected to the lower linkmember 20, having downwardly extending bristles for rubbing paint fromthe synthetic grass surface 13 when the lower link member 20 ispositioned in an operative position, whereby the bristles of therotating brushes 24 are in contact with the synthetic grass fibers 15.While three rotating brushes 24 are provided in this preferredembodiment, it is to be understood that as few as one single rotatingbrush can used. The number and size of rotating brushes employed willdepend on the size of the paint removal device 10 and the size of theintended field installation for which it is to be used. Other factorswhich will affect the number and size of rotating brushes used includethe time allocated to remove the painted field markings and the ambientair temperature. The rotating brushes 24 generally rotate aboutsubstantially vertical rotation axes, transversely aligned along thelower link member 20. However, as best seen in FIG. 2, the axis ofrotation of each rotating brush 24 is eccentrically offset from thecenter of the circular rotating brushes 24. This causes each rotatingbrush 24 to cover a larger area of field surface as it rotates.Preferably, the rotating brushes 24 rotate in contra-rotatingdirections, namely each brush rotates in a direction opposite to that ofthe next adjacent brush. However, the brushes can all be rotated in thesame direction. Rotating the brushes in contra-rotating directionshowever appears to provide the best paint abrading action, in order tobetter remove the paint from all surfaces of each synthetic grass fiber15. The rotating brushes 24 can be made of any selected diameter, inorder to permit selected width of paint to be removed in a single passof the paint removal device 10. It is essential that the rotatingbrushes 24 comprise fine, non-damaging and very low abrasion bristles,such that the synthetic grass fibers 15 are not damaged over the courseof the life of the field. The fine bristles of the rotating brushes 24are designed not to damage the grass fibers, as repeated brushings atthe same location can otherwise sufficiently damage the grass fibers tocreate permanent marks in these locations even when the paint has beenremoved, making these paint-less regions even more obvious from adistance. Generally, the synthetic grass fibers 15 are composed of atleast one of nylon, polyester, polypropylene, polyethylene or anotherplastic, and the type of rotating brushes 24 used should be selectedsuch that the bristles will not cause any significant wear to thesefibers. In a preferred embodiment, the bristles of the rotating brushesare approximately 2 inches in length and made of natural bristle fibers,which are less abrasive than synthetic brush bristles.

By applying a constant pressure on the links 18 of the brush engagingmechanism 16 using the actuator 21, a selected amount of down force canbe maintained on the lower link member 20 to retain the rotating brushes24 in contact with the synthetic grass surface 13. Each rotating brush24 can also have an independent suspension mechanism provided to betteraccommodate uneven terrain, such that painted regions on the syntheticgrass surface 13 will not be missed as a result of bumps in the fieldsurface. The rotating brushes 24 are preferably driven by individualmotors 26, although a single motor could be used to drive all of thebrushes via a transmission system. Both the amount of down force appliedto the rotating brushes 24 by the actuator 21 and the speed of themotors 26 can be selected and controlled by the operator, such that adesired paint removal rate can be achieved. This removal rate will alsodepend on the forward speed of the vehicle 12.

Connected to the rear of the lower link member 20, aligned behind therotating brushes 24, is a static drag brush 28 which extendstransversely relative to a direction of forward travel of the vehicle12. As the drag brush 28 is fixed to the lower link member 20, it isaccordingly raised and lowered with the rotating brushes 24. Thebristles of the drag brush 28 are therefore only in contact with thesynthetic grass fibers 15 of the synthetic grass surface 13 when thelower link member 20 of the brush engaging mechanism is in the operativeposition, wherein the rotating brushes 24 are also in contact with thesynthetic grass fibers 15 ahead of the drag brush 28. The width of thedrag brush 28 is preferably at least as wide as the rotating brushes 24.The bristles of the drag brush 28 are stiffer than those of the rotatingbrushes 24. The drag brush 28 acts to fluff up the synthetic grassfibers 15, which can become depressed by the rotating brushes 24, as thepaint removal device 10 moves forward, This provides a better finalaesthetic appearance of the synthetic grass surface 13 once the paint offield markings has been removed. Further, the drag brush 28 tends tobreak up the surface tension of any small pools of liquid which mayform, used in the paint removal process, which can form on the syntheticgrass surface 13. The drag brush 28 also acts to smooth out any infillwhich has been displaced by the pressurized water spray, which isdescribed in further detail below.

As seen in FIG. 1, the paint removal device 10 preferably includes aforward projecting wand 34, extending ahead of the vehicle 12 and beingaligned with the rotating brushes 24, the wand 34 having a nozzle 32 atan end thereof. The nozzle 32 is preferably adapted for spraying aselected paint-dissolving solvent onto the synthetic grass surface 13well ahead of the rotating brushes 24. However, this forward nozzle 32can also be used to spray water or a water-solvent mix onto the fieldsurface. The solvent nozzle 32 is in fluid flow communication with asolvent storage tank, preferably disposed on the displaceable vehicle 12of the paint removal device. While the type of solvent used will dependon the type of paint to be removed, only environmentally friendlysolvents are preferably used, as they are to be diluted, washed throughthe synthetic grass surface 13 and drained away. The solvent, orcatalyst, used is selected such that it is capable of dissolving theline marking paint without damaging the grass fibers 13. The solventalso must not cause the removed paint material to become clumpedtogether, as such dissolved paint clumps can remain retained in theinfill layer 19, causing a residual visual effect of the removed line orfield marking. The totality of the line marking material and thecatalyst must be able to be flushed down through the turf pile andthrough the artificial grass surface by the pressurized water spraysdescribed in further detail below. The solvent is applied to the paintedregion of the synthetic grass surface 13 ahead of the vehicle 12, suchthat the region is pre-soaked by paint-dissolving solvent before therotating brushes 24 reach the region. This permits the field markingpaint to begin dissolving before the paint is abraded by the rotatingbrushes 24, which allows for more efficient removal of the paint fromthe synthetic grass fibers 15. The paint removal device 10 depicted inFIGS. 2 and 3 is shown with the forward the solvent spraying wand 34removed. If desired, the paint-dissolving solvent can be independentlyapplied to the field surface ahead of the vehicle 12, such as manuallyor using a separate solvent spraying applicator. This may be useful ifthe solvent is required to soak into the field surface for a longeramount of time or requires more time to react with the paint, before therotating brushes are passed thereof to brush the paint from thesynthetic fibers. Additionally, the length of the solvent spraying wand34 can be varied, such that the reaction time of the solvent acting onthe paint before the arrival of the rotating brushes is controlled. Thisis also dependent on the vehicle speed and ambient air temperature.

While solvent is preferably applied on the synthetic grass surface byspraying using the solvent spraying wand 34 and the nozzle 32, alternatemeans of applying the solvent to the grass surface can also be used.This may be useful in situations where spraying the solvent is lesspractical, such as in very windy conditions for example. In this case,direct application methods can be used to apply the solvent to thesynthetic grass surface. For example, a sponge-roller assembly can beused to directly contact the grass fibers to deposit the solventthereon.

At least one nozzle 36 is provided on the lower link member 20 adjacentthe rotating brushes 24 and oriented to project a spray of pressurizedfluid downward into the synthetic grass surface 13 proximate to thebristles of the rotating brushes 24. Preferably, several nozzles 36 areprovided, located at least between each of the rotating brushes 24, andare adapted to spray pressurized water into the synthetic grass surface13 proximate the rotating brushes 24. A rear water nozzle 36 is alsolocated behind the static drag brush 28. All of the water nozzles 36 arein fluid flow communication with a pressurized water source, such as awater tank disposed on the vehicle 12. The water nozzles 36 directcalibrated, high pressure sprays of water into the synthetic grasssurface 13 to help the paint removal from the grass fibers 15 and inorder to flush the dissolved marking paint down through the infill layer19 and through the bottom of sheet backing 17 of the synthetic grasssurface 13. A relatively large amount of water is preferably used inorder to ensure complete removal and disposal of the dissolved paint andthe solvent through the grass surface, such that the area that has beencleaned of paint is thoroughly soaked and the volume of water carriesthe diluted paint deep into the synthetic grass pile and through thesheet backing 17. Preferably, hot water at a relatively high pressure isused to achieve best results. However, it is to be understood that thetemperature must remain below the melting point of the plastic used tocreate the grass fibers 15. Also, the pressure must be calibrated suchthat it is not so high that the infill of the synthetic grass surface issignificantly displaced. While the nozzles 36 disposed on the lower linkmember 20 adjacent the rotating brushes 24 are preferably used to sprayhigh pressure water onto the synthetic grass surface, they can also beused to spray a mixture of water and paint-dissolving solvent, or can beindividually fed such that one sprays only solvent and the others spraypressurized water. A surfactant can also be added to the water, to thesolvent or to the mixture thereof. The surfactant improves the viscosityof the mixture and the dissolved paint, such that it can more easilyflow down through the grass surface for drainage away therefrom. Whileflushing the dissolved paint and solvent down through the grass surfaceis preferably used, alternate means of removing the dissolved paint andsolvent from the grass surface can also be used. For example, a largewet/dry type vacuum device can aspirate any dislodged or dissolved paintand solvent fluid mixture in order to completely remove it from thefield surface. This may be useful in a particularly astringent solventis required, or if the paint is not completely dissolved and suspendedin the solvent fluid.

Although the vehicle 12 is depicted in FIGS. 1 to 3 as a ride-on typevehicle, a walk-behind type vehicle can also be used in order to bettersuit the needs of smaller venues. Such a scaled-down walk-behind unitmay have fewer rotating brushes and may require less water nozzles.

Referring to FIG. 4, an alternate painted field marking removal device50 is shown, which provides a wider paint removal system which ispreferably adapted for removing logos or other relatively large paintedsurface areas from athletic field surfaces, such as end zone paintedlogos on a football field for example. The paint removal device 50operates similarly to that of the paint removal device 10 of the firstembodiment of the present invention. The larger area paint removaldevice 50 comprises a vehicle frame structure 52 disposed on castor-typewheels 54 such that the vehicle can be easily displaced on the fieldsurface. To the main vehicle frame structure 52 is engaged a moveablesub-frame assembly 56 which can be raised and lowered relative to themain vehicle frame structure 52 using an engagement-disengagementmechanism; which includes link arm members pivotably linking thesub-frame assembly 56 to the main vehicle frame structure 52, and anactuator 72 which raises or lowers the sub-frame assembly 56. Threelarge diameter rotating brushes 64 are operatively connected to thesub-frame assembly 56 and are driven by individual brush drive motors66. The three rotating brushes 64 preferably contra-rotating, eachrotating in a direction opposite to that of an adjacent brush. However,the brushes can all be rotated in the same direction. In the preferredembodiment shown, the rotating brushes 64 each have a diameter ofapproximately 20 inches, and are slightly overlapped such that a stripof paint approximately 56 inches wide can be removed as the vehiclemoves forward. However, it is to be understood that the number ofbrushes and their size could be increased in order to provide a largerpaint removing device, for example in order to speed up the removal oflarge areas of painted field markings. An individual suspension systemfor each rotating brush 64 is provided. This is important, as therelatively large, flat rotating brushes 64 are not individuallysuspended, they may skip over painted regions if the field surface isuneven.

A forward solvent wand 58 extends preferably transversely across thepaint removal device 50 along the front edge thereof. The solvent wand58 provides paint-dissolving solvent to several solvent nozzles 60 whichspray the solvent onto the painted field surface in front of therotating brushes 64. A transversely extending water wand 62 is alsoprovided, and feeds a plurality of water nozzles 63 such that a largevolume of pressurized water can be sprayed over the synthetic grasssurface adjacent the rotating brushes 64 and at the rear of the vehicle.

Attachment points 51 are provided on the main vehicle frame structure 52for engagement with another motorized vehicle, such as a small ride-onathletic field tractor or cart for example. This permits the largerpainted field marking removal device 50 to be selectively engageable toa vehicle, for use when required. However, it is to be understood thatthe painted field marking removal device 50 could be permanently fixedto a self propelled vehicle such as that depicted in FIGS. 1 to 3, forexample.

During development of the paint removal apparatus of the presentinvention, the apparatus underwent several trials and iterations beforearriving at the preferred embodiment described above. For example, asingle rotating natural bristle brush was first tested on a syntheticgrass surface having a 2½ inch pile height, with four water nozzleslocated around the rotating brush. While results were nevertheless good,not all of the paint was completely removed. Two more brushes were thenadded, and adjacent brushes were rotated in contra-rotating directions,in order to ensure that the brushes made contact with as many sides aspossible of the synthetic grass fibers. More high pressure water nozzleswere also added around each rotating brush, and the solvent sprayingnozzle was located far ahead of the first brush, such that the paintdissolving solvent was projected onto the field surface in sufficienttime before the arrival of the brushes to be able to soak into thesynthetic grass surface. The length of the bristles of the rotatingbrushes was further reduced to two inches. All of these changesgradually improved the effectiveness of the paint removal apparatus.

During experimental tests of the present invention, various differenttypes of paints and solvents were used, in combination with the sprayedwater and rotating brushes. Additionally, different combinations of thethree elements of the present invention, namely the rotating brushes,the pressurized water spray and the paint-dissolving solvent, weretried. Tests were done that conclusively confirm that neither one partof the paint removal system works optimally without all three componentscombined together. Test were done using only a high pressure spray withwater on the painted lines and a majority of the lines were not removed.Tests were done using the rotating brushes exclusively with water sprayand that was not successful. Tests were also done using onlyhigh-pressure water spray and solvent, which were also unsuccessful.However, when combining all three elements together, the high-pressurewater spray, the paint-dissolving solvent and the rotating brushes, thesystem worked best to remove painted field markings from a syntheticgrass surface.

During these tests, the use of a specially formulated paint which wasless permanent was considered, such that the paint was more easilyremovable by means of either hot water, cold water, high pressure spray,or environmentally friendly solvents that could break down the bindingqualities of the paint and therefore be more easily scrubbed away.However, following several trials, a few examples of which are outlinedbelow, it was determined that regardless of the type of solvent or paintused, the most effective method for removing the paint was thecombination of all three components of the present invention together,namely the rotating brushes, the pressurized water spray and thepaint-dissolving solvent.

Many different solvents were tried, in varying quantities relative tothe quantity of diluting water being used, in order to determine howmuch solvent was required to adequately move the paint from the fieldsurface.

EXAMPLE 1

Simple Gree™ solvents: Simple Green™ pure at the rate of 1 gallon for70′ linear feet; Simple Green™ and water in a 50/50 mix did 120′ linearfeet; Simple Green™ at the rate 1 gallon for 10 gallons of water.

EXAMPLE 2

Soy Solv™ solvents: Soy Solv™ pure at the rate of 1 gallon for 60′linear feet; Soy Solv™ 1 gallon for 1 quart of water can do 65′ linearfeet; Soy Solv™ and water in a 50/50 mix can do 120′ linear feet. Thissolvent left an oily film on the fibers.

EXAMPLE 3

Soy Solv II™: Soy Solv II™ pure at the rate of 1 gallons for 70′ linearfeet; Soy Solv II™ 1 gallon per 1 quart of water can do 75′ linear feet;Soy Solv II™ and water at the ratio of 50/50 mix can do 120′ linearfeet.

EXAMPLE 4

Soy Solv II Plus™: Soy Solv II Plus™ pure at the rate of 1 gallon for70′ linear feet; Soy Solv II™ Plush 1 gallon per 1 quart of water can do75′ linear feet; Soy Solv II Plus™ and water at the ratio of 50/50 mixcan do 120′ linear feet. Soy Solv II Plus™ has an ingredient thatenhances rinsing ability.

EXAMPLE 5

Graffiti Remover™ solvents: Graffiti Remove™ at the rate of 1 gallon for70′ linear feet; Graffiti Remover™ at 1 gallon per 1 quart of water cando 80′ linear feet; Graffiti Remover™ and water at the rate 50/50 mixcan do 120′ linear feet.

The linear distance numbers are of course relative to the speedapplication and the nozzle opening. All of these solvents where testedusing both cold and hot water for mixing and rinsing. Using hot waterappears to work better than using cold water. Some other solvents testedinclude D9™, Gat™, and gasoline. Some solvents leave a slippery oilyfilm and do not dissolve fast enough. This is disadvantageous as thefield cannot be used immediately following the paint removal process hasbeen completed. Also, while some solvents dried non-slippery, a slightamount of moisture, such as from mist or dew for example, can cause theregion to become slippery. Therefore, the relatively large amount ofwater which is sprayed on the synthetic grass surface by the presentinvention is important to ensure that the diluted paint and the solventis flushed deep into the infill layer and through the sheet backing ofthe synthetic grass surface.

Tests were also conducted, using the different solvents, on differenttypes of paint. Some of the paints tested include Pioneer™ paint, WorldClass™ paint, Sico™, Sherwin Williams™, Xerus™ coating, Liquid Chalk™,Krylon™ marking chalk and others. Methods of applying the paint to thesynthetic grass surface were also experimented with, as this can affectthe ability to subsequently remove it.

As a result, it was found that the spray pressure used to apply thepaint is significant to the durability of the painted markings and tothe effect produced on the synthetic grass surface, especially onehaving an infill layer between the synthetic grass fibers. If a veryhigh painting spray pressure is used, most of the paint tends to pushdown through the top grass fibers and reaches the pile, or infill,leaving little paint on left on the fibers. Accordingly, using a lowpaint spray application pressure, between about 20-50 psi, appears togive the best result wherein the paint is deposited mostly on thefibers. This is a radical departure from common paint sprayingpractices, where a spray application pressure of greater than 1500 psiis commonly used. Further, spraying the paint at an angle, preferably 45degrees, dispenses the paint onto the synthetic grass fibers as desired.Painting with the spray nozzle in a vertical position causes much of thepaint to be applied to the infill, which is not desirable. To achievebest results, two paint angled nozzles are used, opposite and facingtowards each other. Additionally, the synthetic grass fibers arepreferably first brushed up before the paint is applied, such that allof the grass fibers can be coated with paint.

As paint which is less permanent is necessarily more easily removed,trials were conducted to modify the paint used such that it containedless binder. However, with less binder, the paint adheres less well tothe fibers. While this permits the paint to be more easily removed, italso does not last as long and become easily worn off, requiringfrequent repainting, which is disadvantageous. While both more costlyand time consuming, requiring frequent repainting means that when itcomes time to remove the paint, there are more coats to remove, whichmakes the removal process more difficult. Therefore, it was found thatvarying the amount of binder in the paint did not greatly improve orfacility the removal process in general. Paints are also now becomingavailable which remain durable for normal playing use, yet are moreeasily removable when desired. Some of the alternate line markingmaterials which were tested include liquid chalk, specially formulatedliquid chalk, and specially formulated latex paint.

The paint removal devices 10 and 50 of the present invention, in eitherride-on or walk-behind embodiments, can also have integrated fieldmarking painting equipment thereon, such that the one device can be usedboth the apply the field markings and to remove them when desired.Accordingly, the integrated device would have the ability to provide ahigh pressure spray for water and/or solvent application, and arelatively low pressure spray for applying the paint to the syntheticgrass surface. Independent control of all sprayed materials is alsoprovided.

The embodiments of the invention described above are intended to beexemplary. Those skilled in the art will therefore appreciate that theforgoing description is illustrative only, and that various alternativesand modifications can be devised without departing from the spirit ofthe present invention. Accordingly, the present is intended to embraceall such alternatives, modifications and variances which fall within thescope of the appended claims.

1. A device for removing painted field markings from a synthetic grasssurface including at least a sheet backing and a plurality of syntheticgrass fibers extending upward therefrom, the device comprising: adisplaceable vehicle adapted to move over the synthetic grass surface;at least one rotating brush operatively connected to the vehicle, therotating brush being engageable with the synthetic grass surface suchthat bristles thereof contact the synthetic grass fibers of thesynthetic grass surface; a solvent nozzle, disposed forward of therotating brush and aligned therewith, for spraying a paint-dissolvingsolvent onto the synthetic grass surface in front of the rotating brush;and at least one water nozzle disposed on the vehicle adjacent therotating brush for directing a pressurized water spray onto thesynthetic grass surface proximate to the bristles of the rotating brush.2. The device as defined in claim 1, wherein three rotating brushes areoperatively connected to the vehicle.
 3. The device as defined in claim2, wherein all three rotating brushes are aligned with the solventnozzle.
 4. The device as defined in claim 2, wherein each of the threerotating brushes rotates in a direction opposite to that of an adjacentrotating brush.
 5. The device as defined in claim 2, wherein the threerotating brushes rotate in a common direction.
 6. The device as definedin claim 1, wherein the rotating brush is disposed on a link memberengaged to the vehicle, the link member being displaceable between anoperative position, wherein the bristles of the rotating brush are incontact with the synthetic grass fibers of the synthetic grass surface,and a non-operative position wherein the rotating brush is not incontact with the synthetic grass surface.
 7. The device as defined inclaim 6, wherein a static drag brush is connected to the link memberbehind the rotating brush, bristles of the static drag brush being incontact with the synthetic grass fibers of the synthetic grass surfacewhen the link member is in the operative position.
 8. The device asdefined in claim 1, wherein a static drag brush is connected to thevehicle behind the rotating brush, the static drag brush beingengageable with the synthetic grass surface such that bristles thereofcontact the synthetic grass fibers.
 9. The device as defined in claim 8,wherein the bristles of the static drag brush-are stiffer than those ofthe rotating brush.
 10. The device as defined in claim 8, wherein thestatic drag brush extends transversely relative to a direction of travelof the vehicle.
 11. The device as defined in claim 1, wherein a waterstorage tank, disposed on the vehicle, is in fluid flow communicationwith the water nozzle.
 12. The device as defined in claim 1, wherein asolvent storage tank, disposed on the vehicle, is in fluid flowcommunication with the solvent nozzle.
 13. The device as defined inclaim 1, wherein the rotating brush comprises natural fiber bristles.14. A method of removing painted field markings from a synthetic grasssurface including at least a sheet backing and a plurality of syntheticgrass fibers extending upward therefrom, the method comprising the stepsof: i)applying a paint-dissolving solvent to a region of the syntheticgrass surface having the painted field markings thereon; ii)brushing theregion using at least one rotating brush to abrade paint coated on thesynthetic grass fibers; and iii)spraying the region with pressurizedwater.
 15. The method as defined in claim 14, further comprisingdragging a static drag brush over the region after passage thereover bythe rotating brush.
 16. The method as defined in claim 14, furthercomprising: providing a displaceable vehicle, the displaceable vehiclehaving the rotating brush operatively engaged thereto behind at leastone solvent nozzle for applying the paint-dissolving solvent onto theregion and including at least one water nozzle for spraying thepressurized water on the region; and moving the vehicle over the regionof the synthetic grass surface at a predetermined speed.
 17. The methodas defined in claim 16, wherein the paint-dissolving solvent is appliedonto the region by spraying.
 18. The method as defined in claim 14,further comprising metering a flow rate of at least one of thepaint-dissolving solvent and the pressurized water.
 19. The method asdefined in claim 14, further comprising spraying the pressurized wateronto the region proximate to the rotating brush.
 20. The method asdefined in claim 14, wherein the synthetic grass surface comprises aninfill layer of particulate material disposed interstitially between thesynthetic grass fibers on the backing sheet, the method furthercomprising flushing the paint-dissolving solvent and any dissolved paintthrough the infill layer using pressurized water spray.
 21. The methodas defined in claim 14, wherein the paint-dissolving solvent is applieddirectly onto the region.
 22. The method as defined in,claim 21, furthercomprising using a sponge-roller assembly, disposed in direct contactingrelation with the synthetic grass surface, to apply the paint-dissolvingsolvent onto the region.